Metallurgical furnace.



C. H. FULTON L W. A. COURSEIL METALLUBGIGAL FURNAGE. v

APPLICATION FILED JULY?, 1911.

Patentea'nec. 24, 1912.

In Ven tors,

UNITED STATESl PATENT oEEIcE.

CHARLES H. FULTON AND WILLIAM A. IGOUBSEN, 0F RAPID CI'JIY,l SQUTHy DAKOTA.

METALLURGICAL FURNACE.

-To all whom 'it may concern:

Be it known that we, CHARLES H. FULTON and WILLIAM A. CoURsEN, both citizens of the United States, residing, respectively, at Rapid City, in the county of Pennington and State of South Dakota, have invented certain new and useful Improvements in Metallurgical Furnaces, of which the following is a specification, reference being had therein to the accompanying. drawings, which form a part thereof. y

Our invention relates to furnaces, Vand i. more particularly to electric resistance furl naces.

The main object of the invention is to pro Vide an electric resistance 'furnace which will develop uniform heat conditions throughout the heated chamber.

A further object is to provide a furnace of this character wherein the resistance ma.

terial is so arranged and the current-is so applied thereto as to secure. equal capacity of the resistance material at every point thereof thereby securing uniform development of heat units by the said resistance material at every .point about the chamber in-y closed by same.

A still further object is to provide a fur-- nace ofl this character wherein the oxygen will be excluded from the resistance material while permitting the convenient addition of such material from4 time to time as required.

A still further object is to provide a furnace of this character, a compact unitary structure wherein the wall of the furnace will contain a plurality of concentric cylinders so constructed and arranged as to con tain the resistance material adjacent tothe heated chamber; to apply the current to said material at every point about said heated chamber; to insulate the furnace as -to the electric current, at all points except through said material; to resist the effect of the` heat upon the furnace; and to prevent heat radiation at all points about the heated chamber. `And a still further object is to provide a Serial No. 687,274.

furnace of this character wherein I'all parts will beso .combined and associated as to inure rlgidlty and permanency inthe struc ure. v i

The invention consists primarily in an electric resistance furnace embodying there in a refractory wall forming a heating chamber, a channel in said wall, completely surrounding said chamber, a granular resistance in said channel, and contact plates adjacent the opposite ends of said wall and in electrical connect-ion with said body of resistance material at all points about said chamber; and in such other novel features of construction and combination -of parts as are hereinafter set forth and described, and more particularly pointed outin the claims hereto appended.

Referring to the drawings 'Figure 1 is a vertical section of a furnace embodying my ein invention; Fig'. 2 is a plan view thereof with sections thereof broken away upon different planes indicated -by the line 2--2 of Fig. 1; and Fig. 3 is a side elevation of the furnace. Like letters refer .to like parts throughout the several views.,

In the accompanying drawings, we have shown a form ofthe invention which in v :practice we-have foundto give 'highly satisfactory results. It comprises an inner tubular section a forming lthe inner wall of the furnace, said sect-ion and all other parts of the furnace wall being preferably circular in cross section. Surrounding the section a is a second tubular section b concen l tric therewith and of a diameter sufficient to form between these two sections a channel adapted to receive granular resistance material. Thesesections in addition to being composed of refractory material are made of material also offering high resistance to an electric current.. `In have found the material whic possesses these two characteristics in a degree to be best adapted for this'use to be magnesia, and we preferably make these two 'sections' of this material. The'channel between the'4 sectionsa and b is filled with a mass of granular resistance material c such as cr tol, crushed graphite or carbon, or any ot er suitable material whichmay be compacted slightly so as to present a substantially uniform volume of this material -at all points -about the section a,.the space within which section constitutes the heated chamber and is indicated by the reference letter d.

ractice we 1.jacket about the resistance material. The magnesia has the twofold function of offerl ing high resistance to the electrical current in a manner to act substantially as anl elecmodate the Vtrical insulator, and also to prevent heat radiation to the outside of the furnace. These various rings are inclosed by a circular jacket g and metallic bands g about the outertubular section e.

The electrical current is conducted to the resistance materiall by means of the plates L and z', which plates are of electricallyhconductive material and provided respectively with suitable binding posts h and These plates vare preferably composed of carbon and are rectangular in contour. In addition to performing their function'as conductors of the electrical current, we utilize these plates to establish ya definite relation of the rings a, b, and e. The lower plate L is provided with a central opening at j, coinciding with the bore of the tubular section a, the edge of this opening being rabbeted at k to form a seat for the said section a and to hold the lower end of said section. The said plate h is also channeled away as at c to receive the lower edge of the tubular section b and space it away from the section a sujliciently to form the channel for the resistance material c. This arrangement also raises the bottom of the said channel above the horizontal 'oint between the said plate and the said tu e, and forms the bottom of said channel of the electrical conducting material of said plate. The upper and lower edges b and e are cut away to accomplates 7L and z' so as to bring these platesflush with the top of said sec'- tions. This construction prevents a rotative movement of the said sections which might tend to rack or loosen up vthe various parts constituting the furnace Wall. The

' upperdpl'ate i has a central opening therein O a, l

ameter approximating'the bore of Vthe section b and the edge thereof is rabbeted as at Z to accommodate the top edge of said section. This construction brings the inner surface of the central opening in 'said plate flush with the inner surface of the section b and exposed within the channel between the sections a and b in a manner to bring it into intimate electrical contact with the resistance material c at every point about the heated chamber (Z when the granular resistance'material is packed within said channel. yThis arrangement also perstay rods 0in a manner to secure all of these parts in the position above described. The lower cap fm, is im erforate and forms a' base for thel entire `rnace while the upper cap n has a central opening therein coinciding with the opening in the plate i thus causing the edge of said opening to form a part of the channel containing the resistance material.

To prevent the burning of the resistance material c through the contact of air therewith, we provide anannular plug p of carbon or other suitable material adapted to fit snugly between the section a andthe cap n, a construction which not only excludes air from .the chamber containing the resistance material, but at the same time permits' said 'channel to be opened at will in'order to renewor replenish the supply of such material therein.

The particular construction of the sections a and b results in that condition wherein the volume of-the resistance material at any point about the section a is substantially the same as at an other point, thereby offering a substantial y uniform resistance to the iow of the electrical current therethrough at all points, or e'ualizing the capacity of this resistance in a manner to develop uniform heat conditions at every point aboutV said section. Furthermore, the plates L and z present continuous contact surfaces of uniform area throughout, about the entire eriphery of the section a, thus distributing the current inv a manner to contribute toward such uniform development of heat..

It is not our intention to limit our invention to the precise details of construction shown in the accompanying drawings, it being apparent that such may be varied with` out departing from the spirit'or scopeof the invention.

Having described our inventioml what wev claim as new and desire to have protected by Letters Patent, is

l. An electrical resistance furnace embodying therein a refractory wall forming a heating chamber and having therein a channel completely surrounding said chamber, a removable plug fitting snugly Within said channel and capable of movement therein, whereby the ,atmosphere is excluded from said channely'a granular resistance in said channel, and contact'plates adjacent to the opposite ends of saidwall and i n electrical connection with said body of resistance material at all points about said chamber.

2. An electrical resistance furnace em-n bodying therein va refractory wall forming a heating chamber and having therein a channel of equal width and depth throughout, com letel surroundlng said chamber, a remova le p ug fittin snugly within said channel and capable o ymovement therein,v

whereby the atmosphere is excluded from said channel, a granular resistance in said channel, and contact plates adjacent the opposite ends of said wall and in electrical connection with said body of resistance ma terial at all points about said chamber.

3. An electrical resistance furnace embodying therein a refractory wall forming.

heating chamber and having thereina channel completely surrounding said chamber, a removable plug litt-ing snugly within said channel and capable of movement therein, whereby the atmosphere is excluded from said channel, a granular resistance in said channel, and contact plates adjacent the opposite ends of said wall, each of said plates presenting continuous contact surfaces of uniform ,width and having electrical connection with said body of resistance materialnection with said body of resistance material at all points about said chamber.

5. An electricalv resistance furnace embodying therein a plurality of substantially electrically nonconductive tubular sections of different diameters whereby the smaller of'said tubes forms a heating chamber and a channel is formed between said tubes completely surrounding said chamber, a removable plug fitting snuglyl within said channel and capable of movement therein, whereby the atmosphere is excluded from said channel, a granular resistance'within said channel,V and contact plates exposed within said channel adjacent the oppo-site ends thereof' and in electrical connectlon with said body of resistance material at all points about said inner tube.

6. An electrical resistance furnace embodying therein a plurality of substantially electrically nonconductive tubular sections of different diameters, whereby the smaller pletely surrounding of said tubes forms a heating chamber and a channel isformed between said tubes completely surrounding said-chamber, a granular resistance within said channel, a lower contact plate having a central circular opening therein of substantially the diameter of said inner tube, a seat formed about sald opening for said inner section, and a channel formed therein'adapted to receive said outer tubular section,land an upper contact plate having an opening centrally thereof of substantially the same diameter as the tubular section having the greater diameter, and a seat formed abo-ut said opening ada ted to receive the top of said section where y said sections are held in a definite relation and said lates are placed in electrical connection wlth said bo-d at all points about sald inner section.

'7. An electrical resistance furnace em bodying therein a plurality of substantially electrically nonconductive tubular sections of different diameters, whereby the smaller of said tubes forms a heating chamber and a channel is formed between said tubes comsaid chamber, a granular resistance withln said channel, a lower contact plate having a central circular opening therein of substantially the diameter of sald inner tube, a seat formed about said nel formed therein adapted to receive said of resist-ance material outer tubular sect-ion, an upper contact plate having an opening centrally thereof of substantially the same diameter as the tubular section having thev greater diameter, and a seat formed about said opening adapted to receive the to-p of said sect-ion whereby said sections are held in a definite relation and said plates are placed in electrical connection with said body of resistance material at all points about said inner section, and an Iannular' closure for the top of said channel between said sections.

8. An electrical resistance furnace embodying therein a plurality of substantially electrically nonconductive tubular sections of different diameters, whereby the'smaller of said tubes forms a heating chamber and a channel 4is formed between said tubes completely surrounding said chamber, a granular resistance within said channel, a lower contact plate having a central circular opening therein of substantially the diameter of said inner tube, a seat formed about said opening for said inner section, and a channel formed therein adapted to receive said outer tubular section, an upper contact plate having an opening centrally thereof of substantially the same diameter as the tubular section having the greater diameter, and a seat formed aboutsaid opening adapted to receive the top of said section whereby said sections are held in a definite relation and said plates are placed in electrical connection with said body of resistance material at l Aall points about said inner section, an annular closure for the top of said channel between said sections, upper and lower caps, and means tying said caps together.

9. An electrical resistance furnace embodying therein a plurality of substantially electrically nonconductive tubularr sections of, different diameters whereby the smaller of said tubes forms a heating chamber and a channel is formed between said tubes completely surrounding said chamber, a remov' able plug fitting snugly within said channel and capable of movement therein, whereby pletely surrounding said chamber, a removableplug fitting snugly within said channel and capable of movement therein, whereby the atmosphere iss excluded from said channel, a granular resistance within said channel, contact plates exposed Within said channel adjacent the opposite ends thereof and in electrical connection with said body of resistance material at `all points about said inner tube, and anl outer wall of material noncoiiductive to heat inclosing said tubular section, comprising a tubular section of substantially electrically nonconductive material, concentric with said other tubular sections and of a diameter sutliciently great tol form a chamber between it and the next smaller section, and powdered heat insulating material within said chamber.

11. An electrical resistance furnace embodying therein a plurality of substantially electrically nonconductive tubular sections of different diameters, whereby the smaller of said tubes'f'orms a heating chamber and a channel is formed between said tubes completely surrounding said chamber, a granular resistance within said channel, a lower contact plate having a central circular opening therein of substantially the diameter of said inner tube, a seat formed about said opening for said inner section, and a channel formed therein adapted to receive said outer tubular section, an upper contact plate havin'g an opening centrally thereof of substantially the same diameter as the tubular section having the greater diameter, and a seat formed about said opening adapted to receive the top of said section whereby said sections are held in a definite relation and said plates are placed in electrical connection with said body of resistance material at all points about said inner section, an annular closure for the top of'said channel between said sections, and an outer wall of material nonconductive of heat inclosing said tubular section comprising -a tubular section of substantially electrically nonconductive material, concentric with said other tubular sections and of a 'diameter suliiciently great to form a chamber between it l and the next smaller sect-ion, and powdered heat insulating material within said chamber.

In witness4 whereof we have each aiixed our signatures in the presence of two witnesses, this 22nd day of June, 1911.

CHARLES H. FULTON. WILLIAM A. ooUR'sEN.

Witnesses:

M. F. CooLBAUGH, A. S. HALLEY. p 

